Robert M. Califf, MD; Deborah A. Zarin, MD; Judith M. Kramer, MD, MS; et al.
Califf and coauthors analyzed characteristics of 96 346 clinical studies registered in ClinicalTrials.gov between October 2004 and September 2007, including the trial sponsors; sizes; and whether randomization, blinding, and data monitoring committees were used. In an 4230, Dickersin and Rennie trace the evolution of trial registries and some issues with the current registration system.